Larger wind turbines: do they generate more energy?

Do larger wind turbines generate more energy?

Yes. Imagine a wind turbine as a giant pinwheel. The larger the blades, the more wind they can ‘catch.’ And more wind means more energy.

The key factor is the rotor diameter, i.e., the area swept by the blades as they spin. When blades spin, they create a circular path in the air. The larger this circle, the more area is covered; therefore, the more wind can be harnessed.

This is based on a simple physical principle: the amount of energy that can be captured from the wind increases with the area swept by the blades. If you double the length of the blades, the area swept doesn’t just double —it increases fourfold! And if the wind blows stronger, energy production skyrockets, as power also depends on the square of the wind speed. A little more wind = a lot more energy.

The energy captured depends on the turbine’s height and blade length.

Larger blades require taller towers. Wind speed increases slightly with height. This means that taller wind turbine towers will capture faster incoming winds, which will result in greater energy production. 

In recent years, wind turbines have grown in both size and power capacity to achieve greater technical efficiency, lower resource consumption, and improved economic performance. In 1985, wind turbines had a capacity of 0.05 MW and a rotor diameter of 15 meters. Modern onshore turbines now have capacities between 5 and 7 MW, while offshore turbines reach 8 to 15 MW. 

In short: bigger wind turbines = more captured wind = more energy generated. That’s why modern wind farms increasingly opt for taller turbines with longer blades.

How do wind turbines work?

The difference in air pressure on the blades caused by wind flow makes the rotor spin, converting kinetic energy into mechanical energy (law of conservation of energy). This energy is transferred through the powertrain to the generator, where it is converted into electricity.

The entire process takes place inside the nacelle atop the tower, which houses key mechanical components (shaft and gearbox) and electrical components (generator and converter). Wind turbines are also equipped with systems that allow them to orient automatically based on wind direction and adjust blade pitch to maximise performance.

What’s the relationship between size, wind, and power generation?

Size is crucial: the larger the rotor diameter and the longer the blades, the more air mass passes through the rotor per second. Therefore, this increases the energy available to generate electricity.

• P = power of the wind (energy per unit of time).
• ρ = air density (about 1.225 kg/m³ at sea level).
• A = rotor swept area = πr², where r is the blade radius.
• v = wind speed.

The relationship between wind speed and energy is not linear —it’s quadratic. If wind speed doubles, the energy captured doesn’t double —it increases fourfold!

As explained by IRENA, this happens because stronger winds (below cut-out speeds) carry exponentially more energy, allowing turbines to produce much more power.

There is also a physical limit, known as the Betz limit (0.593). This limit defines the maximum amount of kinetic energy from wind that can be extracted by an aerodynamic rotor.

How have wind turbines and wind energy generation evolved?

According to IRENA’s Future of Wind report, increasing hub heights and blade lengths has allowed turbines to generate more power without increasing wind resource availability.

Combined with improved operational efficiency and better site selection, these advances boosted the average global capacity factor of new projects from 27% in 2010 to 34% in 2018.

This trend is expected to continue worldwide, with larger turbines and advanced technologies being deployed in key markets like China and India.

Improving the operational efficiency of onshore wind farms, such advances project global average capacity factors of up to 55% by 2030 and 58% by 2050 —significantly higher than the 34% seen in 2018.